Touch screen panels used for displays, such as Liquid Crystal Displays (LCDs) and Plasma Display Panels (PDPs), Light Emitting Diode Displays (LEDDs), or Cathode Ray Tubes (CRTs), are generally attached to the front surfaces of the image display units, and are used as auxiliary devices.
There is a disadvantage in that the touch screen panel degrades the inherent characteristics of the display. A substrate identical in size to that of the image display must be placed over the display unit in order to form a touch screen panel. Therefore, the overall thickness of the display is increased. Furthermore, optical characteristics may be degraded due to the light transmittance of the touch screen panel and the occurrence of a Newton's Ring phenomenon due to light interference effects in the gap between the display unit surface and the touch screen panel, and within layers included in the touch screen panel.
For example, a resistor contact-type touch screen panel has a structure, which may include a transparent conductive layer made of Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO) or the like, a spacer, and an air layer in the space between an upper plate and a lower plate. Newton's Rings are common in this structure.
In another example, a capacitive type touch screen panel may include a dielectric layer (which may include, for example Sb2O5), a conductive layer (such as, for example, a silver or silver alloy) for maintaining a predetermined voltage across the front surface of the touch screen panel, and a separate ITO film layer for blocking static electricity generated from an LCD panel are formed throughout the front surface of the active area of a display. Due to the complexity of such a touch screen panel structure, degradation of the characteristics of the display is inevitable, as described above.
Furthermore, the most commonly used touch screen panels may currently have upper size limitations, as they are mainly composed of a plurality of layers and complex circuitry disposed over the entire screen which scales with display size. Consequently, touch screen panels have been used only with computer-type monitors until now, and commercialization for use with large screen televisions has been relatively low.
Furthermore, considering that mobile applications trend toward thin displays while maintaining high resolution and optical quality, the challenge and motivation to provide a slim touch screen panel technology are significant.
Both mobile and large stationary displays show competitive trends towards high resolution, thinness, multi-functionality, and the integration of separate functions with fewer parts. Thus, there is strong motivation to integrate touch screen panel structures in the display and provide multiple functions while maintaining high image quality display characteristics.
All of the touch screen panels used as described above have structures based on separate touch screen panels that must be added to the display. As a result, there is a need for a touch screen panel that is manufacturable in a form integrated with the display area rather than as a separate panel, while maintaining high image quality.